Thanks guys, think I am starting to understand now
Am I right in saying though I needed to root the phone first before making a backup? I could not of used the restore program without rooting, right?
Right. You can only do the complete phone backup because you have flashed recovery during the rooting process. One of the benefits of rooting
So, I need to make sure that however I partition my 4gb card, the system partition is big enough for this initial system partition to fit on? Is partitioning permanent?
No! The system partition is in the phone's internal memory, not your 4GB microSD card. The phone's internal memory is split into three partitions: system/cache/data
system is where your system is installed,
cache is used for caching purposes, and the
data partition is where your apps get installed when you've downloaded them from the market (Google Play) and
data is the partition that usually gets full up, causing you to run out of space for apps.
The thing is, stock htc Sense rom uses a system partition of 250MB which is HUGE, leaving hardly any space for the data partition and apps!
The default memory allocations are 250/40/147, so you can see that if you install a nice small rom like SUroot's dGB, weighing in at a whopping 60MB, you can shrink the system partition down to 60MB and increase the data partition by 190MB to 337MB, giving you 60/40/337.
The cache partition also doesn't need to be that big and you can happily shrink it down to 5MB which would free up another 35MB, giving you a total of 372MB if I've got my sums right.
I personally would give the system a little breathing space and allocate 70MB just in case at a later date you wanted to insert system apps of your choosing that needed more space.
But I wouldn't worry about the partitioning at first. Just backup your current system and then wipe the memory and flash a new rom. The tiny rom will be rattling around in a cavernous HTC Sense system partition, but it doesn't matter at this stage. You just want to see if it works. Then once you're happy and have installed your favourite apps and your contacts, etc., do another backup of your new system and then you can start playing around with the hboot partitions.
Remember. As long as you haven't changed the original hboot partition sizes, you can restore back to your original Sense system!